The subject invention relates to electrical connectors, and specifically, to non-insulated connectors which are used in conjunction with printed circuit boards. One type of connector contemplated is commonly known as a non-insulated pin jack, and consists of a tubular round shell having a closed end and an open end, and a contact member contained within the shell for receiving and retaining a wire lead or pin. The jack is inserted into the hole of a printed circuit where it makes electrical contact with the conductive plating or pad surrounding the printed circuit board hole, and electrically connects the circuitry on the printed circuit board with that connected to a wire lead or pin received within the shell member. Typically shorting jack shells are either machined or drawn components, both types having inherent shortcomings. For example, machined shells are relatively expensive to manufacture, and by necessity, include a larger outside diameter than can be tolerated in many applications. Drawn shells, while able to be formed with smaller outer diameters than machined shells, cannot be readily provided with retention means which permit the use of the connector in printed circuit boards having apertures of varying diameter, and enable the connector to be securely held in place during handling and soldering. For example, knurling is one retention means generally applicable to machined shells. However knurling thin walled, drawn shells of small diameter is relatively costly and often results in incomplete teeth, i.e., large flat areas rather than sharp crests, and thinning of walls at roots due to tool penetration, thus inviting cracking. Another means for providing a retaining feature, is to form corrugations on the surface of the shell. However, this is not practical with thin walled drawn shells, due to the fine pitch usually required for such applications. Similarly, retaining means such as ribs have been found to be impractical. More particularly, ribs are generally formed under high transmitted tool pressure and are not deformable or flexible. Thus, there is positive displacement during insertion into printed circuit board mounting holes causing a direct reduction of the shell inside diameter equal to the interference between the outside diameter over the rib area and the printed circuit board aperture plus double the rib height. This interferes with and prevent a normal spring contact motion.
One further retention means thought of has been the deforming of the drawn shell by externally applied pressure such that the shell is provided with an oval or tri-lobular cross-section. However, such retention means has been found to have several shortcomings. Firstly, jacks including said retention means are generally unable to enter a printed circuit board aperture freely to an acceptable depth and to remain square to the board surface prior to final seating when used in conjunction with multiple piece vacuum loading devices. Secondly, there is often interference with track members and other tooling used when the jacks are inserted by automatic single piece insertion machines. Thirdly, jacks with this retention means have diameters over the tri-lobular configuration which are too large for many applications, the large diameter being dictated by the pin or wire lead diameter, plus the contact outer diameter. It will be noted that the relationship between the shell inside diameter and the contact outside diameter is an important factor with respect to the proper operation of the jacks. For example, limited shell deformation results in loose jacks when the printed circuit board apertures have diameters slightly larger than those of the jacks. Similarly, when the printed circuit board aperture diameters are slightly smaller than those of the jacks, strangulation and deformation of the contact can occur.
It will further be noted that when these round or knurled shells which are loose in the printed circuit board apertures are soldered, objectionable solder joints often appear. Regarding ribbed, oval, or tri-lobed shells, there is often an excess space between specific locations on the shell and the edges of the printed circuit board, again causing soldering problems.
Accordingly, it is an object of the subject invention to provide a non-insulated connector which is relatively inexpensive to manufacture and which can be readily formed so as to be able to be used with printed circuit boards having apertures of varying diameter.
It is a further object of the subject invention to provide a non-insulated printed circuit jack which, after partial insertion into a printed circuit board, remains in a stable, perpendicular position until sufficient axial force is applied thereto to drive the shell of the circuit jack to a desired depth in the printed circuit board.